Murine virus (FLV)-induced erythroleukemic cells can be induced to differentiate along the erythroid pathway when grown in the presence of DMSO of DMF. These cells are being examined for any changes in enzymes known to be involved in purine metabolism and differentiation of erythroid cells. The effects of FLV infection on the proliferation and differentiation of non-erythroid stem cells are also under investigation. BIBLIOGRAPHIC REFERENCES: Reem, G.H. and Friend, C.: Purine metabolism in murine virus-induced erythroleukemia cells during differentiation in vitro. Proc. Natl. Acad. Sci. 72:1630-1634, 1975. Tsuei, D. and Friend, C.: Comparison of biochemical and biological properties of three strains of Friend leukemia virus (FLV). 75th Ann. Mtg. AM. Soc. Microbiol., New York 1975 (Abstract).